The goal of this project is to examine the effect of naltrexone, an opioid antagonist, on voluntary alcohol consumption in non-treatment seeking alcohol dependent volunteers using a laboratory self- administration paradigm. We have recruited 51 subjects, of which 18 have completed all three laboratory sessions. The data from the first two lab sessions (completed by 41 subjects) is being analyzed. The third lab session which was different from the first two sessions, provided subjects with the opportunity to either drink up to 8 drinks or choose to obtain the monetary value of each drink. Preliminary analysis of the data from this session indicted that subjects who received naltrexone consumed significantly less number of drinks and achieved lower BAC levels than subjects who received placebo. Naltrexone subjects also reported significantly lower levels of craving for alcohol. The results indicate that the new paradigm provides a sensitive method of assessing the effects of pharmacotherapies on alcohol self-administration. Recruitment for this grant has been completed.